1. Field of the Invention
This invention relates to a magnetism generator, in a plasma enhanced semiconductor wafer processing chamber, for generating a magnetic field in a reaction chamber.
2. Description of the Related Art
Some of the semiconductor manufacturing chambers such as a dry etching chamber and a chemical vapor deposition (CVD) chamber manufacture semiconductor devices with plasma formed in a reaction chamber. Some of such semiconductor wafer processing chambers are of a type in which a magnetic field is produced within the reaction chamber by providing a plurality of electromagnets around the reaction chamber to accelerate formation of the plasma.
With this conventional technique however, the intensity of the magnetic field tends to be greater on the edge of a wafer placed in the reaction chamber than in the center of the wafer. Therefore, when this method of producing a magnetic field is applied to the dry etching chamber, there is a problem that the etch rate and the selectivity are not uniform over the wafer surface. When the method is applied to a CVD chamber, there is a problem of nonuniformity in the film formation upon the wafer surface. Still another problem is that the electrical components formed on the wafer suffer charging damage due to a non-uniform plasma density.
Therefore, there is a need in the art for a method and apparatus for controlling a magnetic field in a semiconductor wafer processing chamber.